Racial and ethnic differences in thymic epithelial tumors: A single-institution retrospective analysis.
Authors: Brice Wuthrich, Rohan Maniar, Emily Heldman, Louis Laniak, Hannah Davis, Fatemeh Ardeshir-Larijani, Aaron John Spittler, Kenneth Kesler, Patrick J. Loehrer
Journal: Journal of Clinical Oncology (2023)

e20649 Background: Thymic epithelial tumors (TETs) are a rare, heterogeneous group of malignancies that arise from the thymus. While the etiology of TETs remains unknown, variation in incidence rates amongst racial/ethnic groups has raised the possibility of germline predispositions. Unfortunately, due to the rarity of this disease, there is a limited understanding of the impact of race/ethnicity on tumor characteristics and treatment outcomes for TET patients. We sought to characterize patient/tumor data and investigate treatment outcomes based on race and ethnicity. Methods: We conducted a single-institution, retrospective database analysis of TET patients evaluated at the IUSCCC from 1979 – 2021 from which clinical annotations were available for 477 thymoma and 164 thymic carcinoma (TC) patients. We identified 112 thymoma and 35 TC patients who were deemed to have sufficient data for evaluation of racial/ethnic characteristics. Demographic/clinical variables and therapeutic interventions, including treatment outcomes, were analyzed. Data was compiled and analyzed using descriptive statistics and the Kaplan Meier method for survival analysis via GraphPad Prism software. Results: Of the 112 thymoma patients, 29 thymoma patients presented with de novo metastatic disease at the time of diagnosis. The median age at the time of diagnosis of all patients revealed a statistically significant difference between White and Black TET patients (53.0 v. 42.0 years, *p = 0.0195). There was a trend towards significance when median age of diagnosis between White and Asian TET patients was compared (53.0 v. 48.0 years, p = 0.0633, NS). Advanced histologic subtypes, include B3 and TC, appeared predominantly in Asian and Black patients at 77.7% and 56.3%, respectively, compared to White patients (44.9%), though the finding was not statistically significant. No statistically significant differences between racial/ethnic groups regarding progression free survival for unresectable or metastatic disease were observed, regardless of histology. There was a non-significant difference in recurrence free survival for resectable thymoma in White (30.0 months) and Asian/Pacific Islander (47.0 months) patients compared to Black patients (24.0 months). Conclusions: Overall, this analysis suggests differences in the median age of diagnosis for patients with thymic malignancies based on race, raising the possibility of inherent biologic differences driving oncogenesis and symptoms at the time of presentation. While no statistically significant differences in treatment outcomes were found based on race and ethnicity, Black patients appeared to experience shorter times to recurrence after definitive surgery. Further studies to understand the mechanistic differences driving tumorigenesis and potential disparities in treatment outcomes are greatly needed in this rare tumor type.